The present invention is directed to reducing drag on the web of a positive displacement sorter. While the invention may be used with a sorter that has been in use for some time and may have experienced degraded performance, it can also be installed with a new sorter as a preventative accessory.
A positive displacement sorter includes a web that is made up of a plurality of parallel slats interconnected at their opposite ends with chains in an endless loop, the upper run of which defines a conveying surface. The endless loop, or conveyor, is driven by an electric motor. A plurality of pusher shoes travel along the slats in order to laterally displace articles carried by the conveying surface, such as to one of a plurality of takeaway spurs. The sorter may further include a driven sprocket assembly that is driven by the electric motor and a non-driven sprocket assembly that is free to rotate. The sprocket assemblies support the chains at opposite ends of the web. Each of the sprocket assemblies is made up of at least two sprockets on a shaft, each for engaging one of the chains.
From time to time, a sorter experiences an increase in drag on the web. Such drag may result in an increase in the electrical current, or amps, drawn by the electric motor driving the web. While an increase in electrical current is an indication that the web is experiencing an increase in drag, or mechanical resistance, it has proven illusive to determine the cause of the increased drag much less to provide a suitable solution that reduces drag and, hence, motor electrical current. An increase in drag may express itself in other ways, such as an increase in audible noise as well as visual appearance of the web itself. Past attempts at a solution for increase in drag have been to adjust oil applied to one or both of the chains. Such solution not only may fail to resolve the problem, it may also result in oil discharge to the floor, or the like.